chassis

My pleasure.

Forgot one:
- machining fixture design and tolerance

seamus2154

Turbo and supercharged engines almost always have forged pistons due to the increased cylinder pressures. Are you sure that part # is a cast piston?? There are different types of aluminum harder and softer that are forged, but this pistion issue appears to be a defective design or quality. we love our GLC but I have no intentions of upgrading the pistons to prevent this. Added the extension on to our CPO for 2 more years and unlimited miles. I hope it blows and they pay for the new one.

chassis

I'm not sure if the piston is cast or forged. In either scenario, the failure points are similar for a forging:

- piston aluminum alloy
- forging die design
- forging progression steps and press tonnage
- cooling process
- heat treatment

Each step above is a potential source of a design error MB is fully responsible for.

exhaustgases

So are these hot V engines? Plastic parts caused the coolant loss? You would think by now a high end or supposed high end manufacture of vehicles would know what sort of materials to use to build a decent engine.
Evidently they are clueless. The problem is they can't use good materials since they are too hard to machine or cast and will slow down production, they charge enough for the cars to afford the better materials but like others say they don't care.
Are all the auto makers making junk ICE just so they can push EV? Materials choice is why the problems exist nowadays. Sub contraction of parts and materials fabrication doesn't help either.
Making sub standard parts is fine as long as the purchase price is lowered accordingly, but its savings for them not you.

chassis

The 4 cylinder engines are not hot vee. There is no vee with an inline 4 cylinder.

MB's current production M177 V8 is a hot vee. No other MB engine is or has been a hot vee, meaning turbos in the valley.

MB isn't clueless, they know they are putting inferior product into the market.

apsmbw

*MB helped me out- failure @ 55K- out of warranty! They covered 50% (all parts) on a 17K bill…
ugh but it’s something.

crconsulting

I think when we talk about piston failures, especially ring land failures, we have to look at detonation/pre-ignition as a possible cause, especially with some of today's creative gas "blends".

Some quick reading below may help, please notice the broken ring lands:

http://garage.grumpysperformance.com...-ignition.208/

https://dsportmag.com/the-tech/educa...-pre-ignition/

Packin4

Posted a reply on a similar thread so this will be short. Check out this article...choose your oil wisely.

https://www.hagerty.com/media/mainte...wsletter_NewDD

MrDave929

We have a 2016GLC that we purchased new from a dealership in the Sacramento area. The car was serviced through the dealership, except for one oil change and service performed by an ASE Certified Mechanic. The car has 29,000 miles on it. Never had problems until a week ago while driving on I-80 when the engine began misfiring, vibrating, and the engine light came on. Limped it off the freeway and had it towed home. Mechanic’s diagnosis is a cracked piston! We did not buy an extended warranty. MBenz refused any help because we had an outside mechanic perform one service, despite all prior services being performed at the dealership. I spoke with our sales person who got back to me and offered only $5,000 on a trade-in value, as they devalued the car by the $18,000 it would cost to replace the engine. When speaking with a service adviser at a local dealership, we were told “this is a known issue by Mercedes that Cylinder 1 runs lean and therefore hot” and Mercedes chose NOT to do a Recall. This is our third Mercedes Benz, and we have never had any issues in the past, nor have we been treated so poorly and so dismissively. There must be something that can be done because pistons are not supposed to crack, especially in low mileage conditions like ours at 29K. Current status: Our mechanic was able to obtain a remanufactured long block for just over $4,500 (through MBenz) and with parts & labor will cost $12,000. We are interested in hearing from others who are similarly situated. Thank you!

crconsulting

I would also test the gasoline in the tank. As mentioned above, one has to doubt if the gas was not within called for octane specification (especially in California) or somehow switched "by accident" or convenience.
Typically, the outer cylinders can run lean on most engines, but that also means it could reach pre-ignition or detonation first, if gas is out of minimum spec. I believe these cars have what 10.5:1 compression?


Sucks for sure....

chassis

Sorry to hear about the experience. The dealer treatment you report is typical of others who had the same piston cracking issue on C300, E300 and GLC300 vehicles. Typical poor MB quality and poor MB customer care.

mikapen

That's too bad if Mercedes is waltzing around the issue. It's expensive in time and money.

However, a manufacturer can't deny coverage for using an outside shop, as long as you have records that show all the prescribed checks and replacements were done according to the MB service schedule..
That's according to the Magnuson Moss warranty Act of 1975.

Aside from your low mileage, would your 2016 be out of warranty, time-wise by now?

What if you first approach the dealer with your outside service records and try to get them officially accepted, kind of under the Magnuson Moss stipulations?
Then as a second step, if you're out of the 48 month time period, ask Mercedes for a Goodwill engine replacement?
​​​​​​I would do step two over the phone to initiate contact and go from there.

Tim S GLC

Hello chassis i have followed this thread with interest as I am about to purchase a GLC and have now ruled out the pre facelift 2019 models with the M274 engines due to the reported issues. What I am now wondering is if the GLC 350D has similar issues or not, as i believe the engine is different from the troublesome M274. Have you come across any information on problems with the GLC350D by any chance? I'm struggling to find info around that which i assume means it must be positive!

Actually should also add i am looking at the facelift models for GLC 2.0 litre, again not seen many issues with the updated engine but happy to be corrected on stuff i may have missed. Thanks

chassis

The M274, M264 and newest M254 are all related. Ignore the marketing from MB, these engines are have hand-me-down design features and share some major components. To me it is evidence that MB is attempting to escape the scene of the crime by making design changes from a problematic engine, starting with the M274. The M264 had a curiously very short lifespan and is now being replaced by the M254.

A 2019 engine failure (piston cracking) has not been reported on this site to my knowledge. I don't view this as signal that the latest engine version is trouble-free, but rather that not enough time has transpired and insufficient number of engines have been purchased by consumers.

Looking into the M274 variants, there are several power levels. In non-North America markets, model designations such as C200 use a lower power version of the M274. Not many, if any at all, failures of these engines have been reported on this site. It could be these are in non-English speaking markets and the owners don't participate on MBWorld, an English language forum.

Others on this site have suggested that a "hot tune" is the cause of piston cracking. This is plausible although hard to prove. Higher power from the same engine can easily by accomplished by MB by "tuning" or increasing fuel flow, turbo boost and cam timing. This in turn would create more stress on parts related to combustion and torque delivery, especially pistons.

My conclusion is the M274 is a poor engine because it is incapable of dealing with its power level over a long (200k miles) life span. Most (all) engine failures have been reported at less than 100k miles, and sadly beyond 4 year warranty window.

My recommendation is a strong "do not buy" for M274 MB models, same for M264 models, if in a market that uses the 180kW version of the engine. M254 is too new to comment on.

https://en.wikipedia.org/wiki/Merced...70/M274_engine

Tim S GLC

Hi chassis thanks for the quick response!

I had a look at the Wiki but I don't see the 350D variant listed, only the 350E:-

• 2015–2019 X253 GLC350e 4MATIC

I assumed as the GLC 350 Diesel would have a different engine as its a six cylinder engine - I'm in the UK btw so acknowledge there is a probably limited Diesel vehicle owners in the US market.

Are you saying the 350D (Euro/UK variant) also has this M274 engine? or were you assuming it was a US market question?

Apologies I should have stated my location as this site appears to be mainly US and Non UK market MB owners.

Model year 350D i'm looking at is a 2018/19 and then buying a few years MB extended warranty on top.

A coupe of examples here:-

https://www.autotrader.co.uk/car-det...tion=on&page=1

https://www.autotrader.co.uk/car-det...es-Benz&page=1


Thanks.

chassis

The GLC350d did not receive the M274 2.0L four cylinder petrol engine. It rather received the OM642 3.0L V6 diesel, which in the U.S. had a very sordid history. Search this site for information.

It is possible, although not definitively proven, that the sorry OM642 performance in the U.S. is related to U.S. diesel fuel quality and programming to meet U.S. emissions. The GLC and the OM642 engine are European products designed and built in Europe, principally to meet European regulations. The U.S version of this engine was a failure sadly, widely agreed by people on this site. MB lost a class action lawsuit on this and settlement compensation is available to qualifying OM642 owners.

The European experience of an OM642 seems to be different than in the U.S. and Canada. Hard to say with certainty because MBWorld tends to cater to English-speaking participants, although not strictly. An exhaustive list of posts from German-market OM642 vehicle owners doesn't seem to be found on MBWorld.

Tim S GLC

Thanks for the info and the engine number, i will research that one.

Vino5

It's the same with our 2016 GLC 300. 58K miles, we took extended warranty. Cannot believe the car engine has such a major problem and it also carries the name Benz. Can't believe we bought trash in the name of Benz. Billows white smoke and the Check engine light code is P0301 ( Cylinder 1 misfire), and we can feel slight loss of power and rough idle and drive. Hope Benz at least gives a different check engine code when they detect piston break. Really frustrated.. Taking it to the dealer next and hope the extended warranty covers this... did it cover for anyone else so far?

seamus2154

We also bought the MB extended warranty. There is a clause that states you must properly maintain the vehicle. So as long as you have proof of oil changes and proper maintenance you will be covered. Since buying the warranty I am more diligent about keeping receipts for the GLC's maintenance. Just eclipsed 60K and did the trans service as required. Receipts.

crackedpiston15

so when I wrote the petition to the NHTSA they accepted it but they wrote me that they were only including the engine on the c300 even though I stated that most of the Benz models with the 300 engine were experiencing the same issue . The reason they said was that the c300 has some diamondlike coating or something on some of the parts so that makes them different for whatever reason. Correction, please see screenshot , they will look into all other models with same engine- not just c300

You should write a complaint on the nhtsa website and mention that it’s a safety issue .

about your extended warranty , I hope they don’t give you the run around or say that they won’t fix it because it’s “a known defect “ or some bs like that … I talked to someone on this forum who was denied by the extended warranty they purchased for 6+ months until they got an attorney - that got them to honor the warranty . Good luck to you guys . Let’s hope for the best .

mikapen

The OM642 lost (?) a class action suit, but they did not violate any emissions standard. I'm not even sure they lost an actual case.

I am an involuntary Party to those cases, and there is no money forthcoming, at least after a few years of endlessly navigating the websites. I had 2 diesels, put 220,000 miles on them and they were flawless.

I don't agree that it has a "sordid history."

I believe the problems you're talking about regarded leaking seals, not engine failures.

chassis

OM642 is arguably the most trouble-plagued MB engine in the 21st century, in the North American market. Experience in other markets besides NA seems to be different. Have a read through this site. Too many problems to list, including seal failures.

mikapen

I've read through this site extensively on the Diesel engine, having owned two from Mercedes, and several other small displacement diesels, starting in 1980.

The only reports I see are oil leaks, potentially causing electrical problems. It's a repeat issue, but it's from not renewing single-use seals when servicing certain components. Not a Mercedes problem, more likely a home repair or Indy shop with little knowledge.

Other than poor maintenance reports or "I saw it on the interweb," unsubstantiated comments, not much on trouble plagued diesels.
There are plenty of unsubstantiated comments about everything. The latest is turn signals.

chassis

Are oil cooler seals service items? What about gummed up intakes and turbo failures? Please summarize the list of OM642 failures reported on this site. Please include timing chain failures in the list.

mikapen

Here's the list of reports that I consider reliable, having good service records, regarding unmolested OM642 engines:
1.

On another topic, with the same criteria, (actually I'm just bringing it back to the original topic of GLC 300), here's my list of reports that I consider reliable, having good service records:
1.

Please don't consider my lists as the definitive source.
​​​​🙂